Fine. Just don't do it the way Clive Barker does. Sometimes he introduces the main character a couple of hundred or so pages in. Kinda annoying because the character in the previous pages just dropped out of sight.
I think it's fine. 8D Heck, you could probably focus on the villains for half a story before coming across a hero that'll get rid'a them. The reverse happens plenty often too.
I just hope it's not that kinda cliche thing where a story focuses on some scene where the viewer has no idea what's happening or who's who, and it's all basically just stuff that won't make sense until later - and theeeeen the next part has a proper introduction and story. 8D